In the signal transmission apparatus such as the imaging apparatus and a display apparatus, an electrostatic discharge protection circuit (ESD protection circuit) is generally provided for protecting inner devices (circuits) with respect to electrostatic input from the outside due to an electrostatic discharge (ESD) phenomenon. For example, an imaging apparatus in which the electrostatic discharge protection circuit is provided between signal lines is proposed in JP-A-2007-294900 (Patent Document 1).